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.i ,t @uitrit tetes garnet @ffice JAMES COLBATH, WORCESTER, MASSACHUSETTS. Letters Patent No. 69,772, elated October 15, 1867; antedated September 28, 1867,

IMPROVEMENTS IN VALVES F01?. STEAM EN GINES.

Beit known that I, JAMES COLBATH, of Worcester, in the county of Worcester, and State of Massachusetts, have invented a new and useful Improvement in Automatic Steam-Valves for StcamIumps, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, making a' Part of this specification, in which-' Figure 1 is an elevation of the valve-chest.

Figure 2 is a longitudinal Vertical section of the same.

Figure 3 is an elevation 'of the cylinder-valve.

Figure 4 is an elevation of the same.

Figure 5 is a transverse section of the cylindcr-valve on the line M N of fig.I 3, and

Figure 6 represents a portion of the piston or valverod.

Similar letters indicate like parts in the several figures.

In all cylindrical valves as heretofore used with a rapid reciprocating motion, the pressure of steam, cour bined with-the weight of the cylinder-valve, soon causes the parts which are in contact with one another to wear off, and thus render the Vvalve leaky and ineiiieient. To overcome this difficulty, to simplify the construction ofthe valve, and insure its perfect operation, is thc object and purpose of rnyinvention; and the invention consists in the employment of a reciprocating piston, in combination with a cylindrical piston-valve, the parts 'of both of which are so constructed and'arranged that when the said piston is moved, by its connection with the operating parts ofthe engine, in one direction, steam will Vbe admitted to the said pistonvalve, and thus cause it to move in the proper direction. l

The invention also consists in an enlarged recess, to extend partially around near the ends of the cylindricapiston-valve, in combination with apertures in the ends of the valve for the purpose of balancing the valve andurcducing the friction on the same. 4

Referring to thevdrawings, A, figs. 1 and 2, represents the steam-chest, supposed to be attached to the top of asteam-cylinder. The piston or valve-rod B passes through the steam-chest, and is iitted in steam-tight stuffing-boxes C C. Within the steam-chest Ais titted, so as to slide freelyfa cylindrical piston-valve, D, which also slides freely on the piston B. The saidpiston-valve D is prevented from rotating within the steam-chest by means of a screw or pin, a, fitting within an oblong recess, b, as shown in iig. 1. The piston-valve D is provided with two annular grooves e e', connected on the upper side by a passage, d, and communicating with the inlet-portsff, leading tothe steam-passages of the steam-cylinder. A chamber, H, on the under side of the valve D, communicates with the `exhaust g. The piston B is provided with steam-passages and with inlet and outlet-ports, as shown in fig. 2 at m m', Z Z, and n n', by means of which steam is allowed to pass from the valve D into the spaces o o at each end of the steam-chest A. The steam from the boiler enters the steam-chest A through the pipe E, over the passage cl,-which latter it fills, and also the two annular grooves ce', and, as the grooves come respectively opposite their corresponding inlet-ports, the steam will pass to the steam-cylinder.

\ This portion of the piston-valve D will thus operate similarly to an ordinary slide-valve. Steam passes through the aperture z', 2, of the cylindrical valve D, and thence through the passages ZZ', m m', and n n', to thc spaces o o', between the ends oi` the cylindrical valve D and the steam-chest heads, and thus 'a reciprocating motion is imparted to the cylindrical piston-valve D, according to the position et the piston B. The valve D is formed with a recess or groove extending around the same, near cach end, as shown at lo q', iig. 3. A portion ofthe said recess q on the under side of the valve is much larger or Vwider than the other portion p', and communicates by means of openings r 'r' with the spaces o o', and thus steam is admitted to the enlarged portion, and, actin-g upon a larger area, serves to 'counteract the weight of the valve D, hy the excess of steam pressure upon the said valve, land thus the latter. becomes a balanced valve. The apertures s s connect the spaces o o' .with the chamber r, which latter communicates with the exhaust g.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. The combination of the piston B,`constructcd as described, witli the cylindrical piston-valve D, operating as andfor the purpose set forthL l 2. The enlarged recesses g' near the ends of the pistonvalve D, in combination with the apertures r t", communicating with the spa-ces o o in the steam-chest, as and for thc purpose specified.

In testimony whereof I have signed my name to this speciiicationin the presence of two subscribing witnesses.

JAMES COLBATH.

Witnesses: A

J. H. ADAMS, DAVID Knnnnn'nn. 

